Your fitness tracker could predict when you're about to get sick

Thanks to all the sensors packed inside, your trusty Fitbit or Garmin could clue you in to a looming immune system battle.

With fitness trackers and smart watches becoming a must-have item among the health-conscious, it was only a matter of time before some curious researchers tried to figure out what all of that data-gathering could really do for us. After all, these wearables are packed full of biosensors that can collect and analyze tons of biometrics: skin temperature, calories burned, heart rate, and steps taken per day, you name it.

Now, scientists at Stanford University are tracking another one: whether you're about to catch a cold.

In a new study, the scientists tracked 43 people for almost a year using an array of devices and recorded more than 250,000 daily measurements based on parameters like heart rate, skin temperature, sleep, daily activity, and total gamma and X-ray radiation exposure.

The most interesting finding? Airplane travel resulted physiological changes like an increase in radiation exposure, and a decrease in blood oxygen levels. The devices were also able to tell the difference between people who were insulin-sensitive (a sign their bodies were efficiently using glucose) and those who were insulin-resistant (a pre-diabetes indicator).

Most strikingly, one of the study authors was able detect the symptoms of Lyme disease before it became full-blown. Michael Snyder, Ph.D.—also a study participant who was wearing eight sensors—recounted in a press release about his catching the early warning signs while on a flight to Norway. “I had an elevated heart rate and decreased oxygen at the start of my vacation and knew something was not quite right,” said Snyder. “Wearables helped make the initial diagnosis.”

Synder is hopeful that in the future the information collected could assist your doctor. “In the long-term, I am very optimistic that personal biosensors will help us maintain healthier lives," he said.